Herring larvae in the North Sea (IHLS)

Project

Conduction of international herring larvae surveys (IHLS) in the North Sea

How many herring larvae are hatching annually? The Thünen Institute of Sea Fisheries estimate their number in annual research surveys. For example, we use this information as an indicator of the spawning stock biomass of North Sea autumn-spawning herring.

Background and Objective

The German contribution to the international herring larvae survey (IHLS) is part of the European Data Collection Framework (DCF). Larval abundance indices are used to estimate the spawning stock biomass of autumn-spawning North Sea herring within the ICES Herring Assessment Working Group (HAWG).

Target Group

science, politics

Approach

During the North Sea herring spawning season, a predefined grid of stations is sampled with the so called Gulf plankton sampler. Fish larvae are sorted from these tows and the length distribution is being measured. The number of newly hatched herring larvae is used to derive an index of the biomass of the North Sea herring spawning stock.

Preliminary Results

We transfer the data to the International Council for the Exploration of the Sea (ICES). Here, the Herring Assessment Working Group (HAWG) make use of the data to provide scientific advice on allowable catches.